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A unique trait about spiders that seems hard to fathom and a geologic milestone make the list this week:

Spiders Able to Catch, Devour Fish: Spiders are known for hunting insects, of course. But fish? Not only is the answer yes, the spiders are rather good at it. So say scientists who have observed at least 18 species of spiders on every continent but Antarctica hunting and feasting on fish.

Introducing the Earth's Most Abundant Mineral: Quick, name the Earth's most abundant mineral. If you uttered "bridgmanite," that means you're clearly up on your geologic news because the mineral just got its name this month. In fact, that's because scientists finally saw it for the first time, thanks to a meteorite.

Soon, Your Cavities May Fill Themselves: What if instead of having a dentist drill and fill your cavities, you could have your teeth painlessly heal themselves? A team of scientists says it has developed a technique that does precisely that. The process uses a tiny electric current to push minerals into the damaged part of the tooth—and it may not be that far off.

Arthritis Drug Makes Hairless Man Very Hairy: It turns out an FDA-approved rheumatoid arthritis drug might just cure baldness—at least the form caused by a rare immune disease. During an eight-month trial of the drug, a 25-year-old man whose body was nearly hairless grew, well, a lot of it, including plenty atop his head, Yale researchers say. He has rare disease known as alopecia universalis.

Skulls From 'Pit of Bones' May Hold Evolution Clues: Since 1984, scientists have been analyzing thousands of bone fragments from the aptly-named "Pit of Bones" cave in Spain, home to the largest collection of ancient human fossils ever found. Now, they say their analysis of 17 skulls thought to be some 430,000 years old sheds light on the earliest Neanderthals—and, potentially, how humans may have evolved. For one thing, bigger brows preceded bigger brains.